This invention relates to a shock absorber of the type employed in the rear suspension for a motorcycle.
Shock absorbers of this type are subjected to heavy duty wear and thus require closely controlled compression and extension damping to provide controlled ride characteristics. In addition, it is desirable to promote maximum stability and traction with the ground. Highly successful shock absorbers of this type are now marketed by Moto-X Fox, Inc. of Campbell, California.
Such a shock absorber comprises a housing having a piston reciprocally mounted therein to define first and second chambers on either side of a head of the piston. The shock absorber is adapted to be partially filled with oil and the first chamber, disposed at the head end of the pistion, is adapted to be air-pressurized. A plurality of ports are formed through the head of the piston and are normally closed by an annular spring washer mounted beneath the head. Upon compression of the shock absorber, the spring washer will function as a bypass valve to communicate oil from the first chamber to the second chamber.
A pair of orifices are also formed through the head to communicate the first and second chambers and function to meter fluid from the second chamber to the first chamber upon extension of the shock absorber. The first chamber further openly communicates with a third chamber defined in the hollow rod of the piston. An inflatable bladder is mounted in the rod and is adapted to be air-pressurized to aid in closely controlling the spring rate of the shock absorber upon compression thereof.
As will be hereinafter described, the shock absorber of this invention constitutes an improvement over the above-described shock absorber and substantially improves extension damping thereof.